588 U. S. BUREAU OF FISHERIES 



but on account of the poor run and consequent very limited catch, 

 the data secured were inadequate as a basis for definite conclusions. 



Two trips were made to Karluk Lake. Limnological data were 

 collected on each trip and observations were made as to conditions 

 on the spawning grounds. This investigation has been carried on by 

 Dr. Willis H. Rich, who was assisted by J. T. Barnaby. 



Chignik red-salmon investigations. — An investigation of the red- 

 salmon runs of Chignik River, Alaska, has been continued by 

 Harlan B. Holmes, associate aquatic biologist, assisted by Sidney B. 

 Hayes and Hugh R. Israel, temporary assistants. Unusual irregu- 

 larities in the growth and migrations of the fish are making it neces- 

 sary to devote considerable attention to preliminary problems before 

 attacking the basic problem of determining how many fish must be 

 permitted to pass up the river to spawn in order to produce the 

 greatest surplus to be taken by the commercial fishery. These pre- 

 liminary problems were discussed in the report for 1929. Investiga- 

 tion of them was started in 1928 by a study of the seaward migra- 

 tion of fingerlings. In 1929 the work was extended to include studies 

 of the life of the j^'oung fish in fresh water and methods of sampling 

 the run of mature fish. The run of mature fish in 1929 was unfavor- 

 able for the study of sampling because the age composition of the 

 run was unusually constant. Plans were made to repeat extensive 

 sampling in 1930, but again conditions were unfavorable; this time 

 as a result of a small run that made it necessary to prohibit com- 

 mercial fishing for the greater part of the season. 



The study of the young fish in fresh water was continued in 1930, 

 particular attention being given to the fish in Chignik Lake, the 

 lower of the two lakes, and to the seaward migrants. The complex 

 situation observed in 1929 was found to prevail again in 1930. Fish 

 ranging from fry that had recently emerged from the gravel of the 

 spawning beds to fingerlings 10 centimeters in length were found 

 throughout the season. Between these limits of size they were dis- 

 tributed in an array that practically defies age analysis by means 

 of length frequencies. It is hoped, however, that further analysis of 

 the data accompanied by a study of the scales of the fish will make 

 it possible to determine "the age of the fish with reasonable certainty. 



The seaward migration of fingerlings, as in previous years, Avas 

 found to extend throughout the summer. Fifty thousand of the 

 migrants were marked by the removal of two of their fins. The re- 

 covery of some of these marked fingerlings several weeks after 

 they had been marked confirmed other evidences of a leisurely mi- 

 gration, a condition quite different from that at Karluk for example, 

 where several million fingerlings pass down the river and disappear 

 in a period of a few weeks. The fingerlings were traced even into 

 the ocean where they were found in all the neighboring baj^s for 

 the greater part of tlie summer. 



Pink-sahnon investigation. — This investigation is concerned with 

 the application of the " parent stream " theory to the life history of 

 the pink salmon and witli the survey of the streams in which they 

 spawn. The latter is being made for the purpose of ascertaining 

 some of the biological factors underlying the fluctuations in their 

 abundance. Dr. F. A. Davidson has had charge of these 

 investigations. 



